1. Field of the Invention
The present invention relates to a method for sealing electroluminescence elements capable of manufacturing electroluminescence elements having excellent display quality.
The present invention relates to a method for manufacturing a plurality of light emitting panels having a light emitting portion by forming a layered body where a plurality of light emitting portions are sealed between a mother substrate and a mother sealing plate, and after that, dividing the layered body into pieces, each of which has a light emitting portion, as well as to a method for manufacturing a plurality of light emitting panels having a display portion by forming a layered body where a plurality of display portions are sealed between a mother substrate and a mother sealing plate, and after that, dividing the layered body into pieces, each of which has a display portion.
2. Description of Related Art
In recent years, attention has been paid to organic electroluminescence (hereinafter referred to as organic EL) elements as self-luminous type light emitting elements, and the development of organic EL displays using such organic EL elements has been progressing. Organic EL elements are characterized by having quick response speed that is appropriate for animation display, low voltage and drive with low consumed power, and therefore, organic EL displays are expected to be next generation displays for next generation cellular phones, portable terminals (PDA's) and the like.
Organic EL displays are provided with an organic EL panel having a plurality of organic EL elements for displaying images, a drive circuit, a drive power supply and the like.
The light emitting properties of organic EL elements deteriorate when making contact with moisture, and therefore, it is necessary to seal organic EL elements so that the organic EL elements do not make contact with moisture in an organic EL panel. Therefore, organic EL panels are manufactured by pasting together an organic EL substrate where organic EL elements have been formed, and a sealing substrate for sealing using an adhesive for sealing.
As a conventional method for sealing EL elements, a method in which an EL substrate and a sealing substrate are sealed with a hardening resin in liquid form that has been dropped onto one of the substrates so as to form protrusions on the substrate is known (Japanese Unexamined Patent Publication 2000-10506). In accordance with this prior art, however, as shown in the plan diagram of FIGS. 2(a) and 2(b), a hardening resin in liquid form 42 spreads into circular shapes on an EL substrate 41 (FIG. 2(a)), and at the time of pasting, this hardening resin in liquid form 42 further spreads into concentric circular shapes, creating spaces 43 surrounded by resin 42, and bubbles are created, due to these spaces (FIG. 2(b)).
When bubbles are created in the adhesive layer between the organic EL substrate and the sealing substrate, the index of refraction in the bubble portions is different from the index of refraction of the surrounding adhesive layer, and therefore, the color of the bubble portions is seen as a different color from that of the surroundings. Thus, a problem arises, such that the shapes of the bubbles can be seen with the human eye when the organic EL display is displayed, and thus, the display quality is lowered. Furthermore, moisture that is included in the bubbles seeps into the organic EL elements so as to cause the light emitting properties to deteriorate, and therefore, the reliability of the organic EL elements is lowered. Accordingly, in order to provide an organic EL display having excellent display quality and high reliability, it is necessary to seal the organic EL elements without creating bubbles between the organic EL substrate and the sealing substrate.
Therefore, a method for sealing organic EL elements without creating closed spaces such as the above described spaces 43 by dropping a hardening resin 42 in liquid form onto one substrate along lines so as to prevent the above described spaces from being created in the resin 42 is described in Japanese Unexamined Patent Publication 2000-10506.
Meanwhile, a manufacturing method that is referred to as multiple panel taking is frequently adopted in the process for manufacturing organic EL display panels, in order to increase production efficiency (for example, Japanese Unexamined Patent Publication 2001-126866). Multiple panel taking is a method for manufacturing a plurality of organic EL display panels by pasting one mother substrate of which the size is sufficiently greater than that of one organic EL display panel and where a plurality of organic EL display portions are provided, and one mother sealing plate of which the size is sufficiently greater than that of one organic EL display panel together, and after that, dividing the resulting layered body into pieces, each of which has an organic EL display portion.
When the dropping method that is described in Japanese Unexamined Patent Publication 2000-10506 is adopted in multiple panel taking, it is necessary to drop a hardening resin in liquid form 42 for each of the number of organic EL display portions on the above described mother substrate, and therefore, the hardening resin in liquid form 42, 42 . . . spreads and is integrated, as shown in FIG. 2, in such a manner that air is left in closed spaces that are surrounded by the hardening resin 42 in liquid form. In the case where such closed spaces are created, air in the closed spaces cannot escape, even when pressure is applied to spread the hardening resin in liquid form 42, and these closed spaces restrict the distance between the mother substrate and the mother sealing plate, and therefore, the hardening resin in liquid form 42 cannot be uniformly spread in the organic EL display portions, and the distance between the two plates cannot be narrowed. Further, even if the closed spaces are compressed so as to uniform the distance between the mother substrate and the mother sealing plate, the area occupied by the closed spaces increase due to the constant volume of the closed spaces. Due to the existence of such closed spaces, as described above, a problem arises, such that the display quality of the organic EL display panels is lowered. In addition, the portions where the above described closed spaces exist in the organic EL display portions are not covered with the hardening resin in liquid form 42, and in the case where the plate is divided into respective organic EL display portions, a problem arises, such that the above described portions are exposed to the open air, and moisture in the open air seeps into the organic EL elements, making the light emitting properties deteriorate, and thus, the reliability of the organic EL elements is lowered.
In addition, when closed spaces are created, as described above, the distance between the mother substrate and the mother sealing plate cannot be reduced so as to be smaller than the height of these closed spaces, and therefore, the distance between the mother substrate and the mother sealing plate becomes greater than a predetermined distance. In the manufacture of light emitting panels or display panels, in some cases, the color chromaticity of light that is emitted is adjusted by setting the distance between the mother substrate and the mother sealing plate to a predetermined distance, and in such a case, when closed spaces as those described above are created in such a manner as to prevent the distance between the mother substrate and the mother sealing plate from being reduced to the height of these closed spaces or smaller, and therefore, the distance between the mother substrate and the mother sealing plate cannot be set to the predetermined distance, and a problem arises, where the color chromaticity of light that is emitted becomes different from that desired, and thus, the display quality is lowered.
A problem arises, such that the manufacture yield is lowered due to the reduction in the display quality and in the reliability, as described above.
As described above, in the case where the manufacturing method for an organic EL display panel that is described in Japanese Unexamined Patent Publication 2000-10506 is applied to multiple panel taking, a problem arises, such that the display quality of organic EL display panels becomes low and the yield also becomes low.